In brickwork masonry a bond is the repeating pattern of headers and stretchers employed to arrange bricks in ascending courses. Various bonds were utilized in the construction of masonry fortifications to increase the stability of the masonry masses forming walls, casemates, and galleries. The most common bonds included:

Flemish Bond, in which headers alternated with stretchers in each course with the headers centered on the stretchers of the preceding and succeeding courses.

English Bond, in which courses of headers alternated with courses of stretchers.

American Bond, in which one course of headers was laid for every three to six courses of stretchers.

In all strong bonds the joints between the bricks of each course were broken in both the preceding and succeeding courses in such a way that a single line of mortar between the bricks did not extend vertically beyond the width of a single brick plus the width of the mortar within the joint.